Flue-heat-utilizing water heater



March 25, 1941. FJELLMAN 2,236.17)

FLUE-HEAT UTILI Z ING WATER HEATER Filed Dec. 7, 1939 2 Sheets-Sheet l Kdlpl; E's/[main b y W azz y March 25, 1941. R. H. FJ'ELLMAN FLUE-HEAT UTILIZING WATER HEATER Filed Dec. 7, 1939 2 Sheets-Sheet 2 Invent-0k.

I x i Patented Mar. 25 1941 UNITED ST TES FLUE-HEAT-UTILIZING WATER HEATER V PATENT OFFICE.

I Ralph H. Fjellman, Niles Center, 111. Application December 7, 1939, Serial No. 307,944 12 Claims. (01.122-20) My invention relates 'to' a water-heater for utilizing otherwise wasted heat of the combustion gases emitted from a heater such as a household type of furnace, which appliance also will serve 55 as a flue elbow for interposition'between a horizontal flue pipe and a-combustion gas outlet in or near to the top of the furnace (or thelike). More particularly, my invention relates to a water heater of this class adapted to be seated on a part of the metal top of a furnace or the: like for also utilizing some of the heatof that topto speed the availability of adequately hotwater, and a water heater having the following advantageous characteristics:

(a) Simplicity of construction, with the flue elbow part and the water container constructed as an integral and easily manufactured metallic unit.

(b) Compactness for allowing a water heater of ample capacity for supplying the usual kitchen, bathroom and laundry requirements of a household, to be disposed on top of a-furnace in a basement of average height. I

(c) Afiording an ample draft, even when chimney or stack is of short height and the barometer is low.

(d) Including an adequate draft control as a built in part of the water heater, thereby elimi nating both the need of a separate draft damper in the flue pipe and the difl'iculties encountered whenever soot collects in that pipe.

(e) Having the water compartment formed so that convection currents speedily permit adequately hot water to be drawn from the upper part of this compartment, and disposing the flue elbow in such relation to this compartment as to be particularly effective in heating the upper part of the water in this compartment; 40 (f) Enabling combustion gases to flow along a short path through the flue elbow when the damper is in or near its full-open position,*and compelling these gases to flow mainly along a much longer path and along a much greater heatconducting area of the water compartment when the damper is in or near its closed position. (9) Providing simple means also (when my water heater is to be used with an oil-burning furnace) for pre-heating oil in a part of the fueloil-supply pipe, thereby decidedly increasing the efficiency of combustion of the oil's'o as to'reduce the fuel cost, and efiecting this oil-heating without risks of fire or explosions. I

(h) Providing all of the above listeda'dvan{ tages in a rugged water heater which'can readily be installed by the average furnace user with the aid of afew pipe-fitters tools. I

Illustrative of the manner in which I accom plish the above listed advantages as well as other advantages:

Fig. 1 is a perspective view of a water heater embodying my invention, showing the frontal outlet end, the damper handle side and the top of the heater; as also portions of the water inlet and water outlet piping, and of an oil-heating pipe.

Fig. 2 is a somewhat enlarged vertical and longitudinal section taken along the line 2-2 of Fig. l and including'the portions of the heater top and of the flue pipe between which my water heater is interposed.

Fig. 3 is a still larger transverse and vertical section, taken along the line 3-3 of Fig. 1.

Fig. 4 is a horizontal section taken along the line A -4 of Fig; 3, drawn on a smaller scale than Fig. 3.

Fig. 5 is a still smaller perspective viewrof the part of mywater heater which constitutes the flue elbow, together with portions of the casing. Fig. 6 is a section allied to Fig. 2 but drawn on a smaller scale, showing the damper in its fullopen position.

In the illustrated embodiment my water-heater includes as its body member a rectangularmetal casing having a gas inlet collar C depending from the bottom B of the casing and fitting a gasoutlet collar h formed from the top H of a furnace or the like on which the said casing is seated. This casing also has an elbow outlet collar 2 projecting from its front and connected to the inlet collar 0 byan inner shell portion which, together with the said two collars, constitutes the flue elbow shown inperspective in Fig. 5.

' This flue elbow comprises two riser sides E. and

E spaced by a distance considerably less than the spacing between the two riser sides S and S of the outershell or casing of my water heater, and a wall member shaped (as shown in Figs. 2 and 5) to'present a riser wall Wv near but spaced from therear riser wall R.of the water heater casing, wall W being continued by an elbow topv part w which arches across the axis a of theinlet of the elbow and is continued by an elbow-top portion w which extends to front wall and merges'with the upper portion of the gas outlet collar 2.

The lower ends" of the sides and the back of the elbow are sealed to the bottom B of the casing and preferably spaced equally from the adjacent riser walls of th'ecasing, while the flue'topparts preferably haveth'es'e highest portions spaced still further from the top T of the rectangular casing,

thereby affording water-housing spaces along the back and both sides of the elbow, and also above the elbow.

Water is admitted to some low part of the said spacing, as by a cold water pipe 3 in Fig. 2; and allowed to be drawn from an upper part of the said spacing, as through a hot water pipe 4, or through a side pipe substituted for a side closure plug 5 when the latter replaces the said hot water pipe.

To facilitate a circulation of the water in the water-container thus afforded by the above described spacings, I also provide a horizontal duct D spanning and opening through the riser walls E and E of the flue elbow part of my device, this duct being freely spaced from other, parts of the said elbow and desirably having its axis a somewhat higher than the axis 1) of "the outlet collar 2 of the fiue elbow.

To control the rate of gas flow through'the said elbow I provide a damper 6 having one edge portion fastened to a dampershaft l disposed below, near and parallel to the axis to the water duct D, this damper having its opposite edge normally seated by gravity on a flue elbow part near the outlet of that elbow as shown in Fig. 3. This damper although sloping downward toward the forward casing end F (as in Fig. 2) in its closure position, can be raised through a considerable angle, as shown by dotted lines in the same figure. The damper also desirably has the usual safety opening 6a to insure a sufficient opening, even when the damper is in its closure position, to avoid damage in case of an explosion within the furnace on which my heater is seated.

Toprovide for a control of the damper from the exterior of my heater I desirably journal the damper shaft 1 in two alined tubes 8 which span the water-housing spaces at opposite sides of the flue elbow part of my heater, each of which tubes has its ends sealed respectively to one side of that elbow and to the adjacent riser side of the casing of my heater. By doing this I prevent water from entering the elbow alongside the damper shaft, and likewise prevent gases within the elbow from intermingling with the water.

One end of the damper shaft also extends beyond the adjacent side of the heater casing, for connection either to a damper handle I0 as partly shown in Figs. 1 and 4, or more indirectly (in a manner well understood by heating equipment contractors) to a thermostatic control responsive to the temperature of the water in my heater.

When my thus constructed water heater is in use with the damper 6 in its closure position of Fig. 3, this damper compels nearly all of the admitted combustion gases to flow (along the dotted arrow line l2) upwards between the transverse duct D and the back W of the flue elbow and then over that duct. Since this path is much longer than the direct path (along the dotted arrow line IS) in which the gases would flow when the damper is considerably opened, these gases spend much more time in the flue elbow and also sweep along the large area of the inner face of the flue wall member which includes the portions W. Consequently, my heater will speedily transfer heat from such gases to the water, and the water heating also will beaugmented by the direct conduction of heat; from the furnace top H through theheaterbottomzportions under-e lying the three parts of my water compartment which together have a U-section as shown in Fig. 4.

When my combined flue elbow and water heater is to be used with an oil-burning furnace, I also provide an oil pipe P extending longitudinally and desirably axially through the transverse water duct D, this tube being exteriorly sealed to the two side walls of the casing of my water heater, as by bushings 15. Thus disposed, the oil flowing through the pipe P will be adequately heated by the water in which it. is immersed, for decidedly increasing the efiiciency of the combustion of the oil in the combustion 'chamberof the furnace. Consequently, my water heater unit then not only will afford an ample supply of water at a temperature suitable for kitchen, laundry and bath-room uses, but also will reduce the oil consumption for the air-heating for which the furnace was installed. Moreover, installations of my water heater have shown that I can accomplish these advantageous results with units of quite small size in proportion to the diameter of the furnace, merely by utilizing part of the heat which otherwise is wasted up the stack to which the flue-pipe p of Fig. 2 is connected.

However, if the furnace or other heating appliance with which my said unit is associated is noto-f an oil-burning type, the oil pipe P and the bushings l5 of Fig. 3 are omitted, and the openings for these bushings are merely closed by solidplugs in a manner tooobviousto require illustration.

By' shaping, disposing and proportionlng the parts of my water heater in the here illustrated manner I obtain both a speedy. availability of adequately hot water and an unusually large utilization of heatof thegases flowing through it, for these reasons:

(1) With thebottom of the metallic heater casing seated directly on the metal top of a furnace or the like, heat is conducted directly from this top of the portions of. the casing bottom which underlie both'the riser shanks and the back of the substantially hood-shaped water compartment, so that convection currents speedily'carrywar'med water to the upper portion of this compartment, inwhich upper portion the water then is additionally heated by heat transfer through the, toplw of; the. flue elbow from the gases in that elbow.

(2) 'By forming the hood-shaped. inner wall member with parallel risersides' spaced by the full diameter "of both the gas inlet and gas outlet, and with a fiat riser back, Igive' the interior of my flueelbow a considerably greater horizontal section than" the bore of the said inlet, as clearly shown in Fig. 4.: Consequently, the gas entering this elbow expands, correspondingly within. the latter, thereby retarding the rate of gas flow so as to prolong the time during which heat is transferred from the; elbow-housed gases to the wat'erbehind, above and alongside the elbow.

(3) By providing myzelbow-forminghood with upright sides andlwith a ,wall portion vsuch as might, bebent from a sheet metal strip of the uniform width of, the, elbow I also obtain much greater interior as Well as exterior surface areas for heat conduction than the. corresponding heat-exchange areas in a circular-sectioned duct havi the; same dia e a d is as: my, casin inletszandputlets.

- (4) By having my. transverse iwater duct D overhang the 'g'asinlet of my heater"casing; I:

impinge directly on this duct, thereby alsoadding a considerable surfacearea to the 'just r'ecited extensive one afforded by my hood-shaped substitute for a mere curved pipe.

(5) By having the entire portion of "the-'oil pipe P within my casing immersed continually in the water with which that'casing is continually filled, I guard against an excessive heating of the oil in this pipe, and also againstthe risks of fire or explosions which would "be expected if the gases impinged directly on that-pipe. I (6) 'By disposing my transverse water duct as here disclosed, I also cause this to serve 'asa bafile spacing the flow of gases along two paths, namely a relatively short and direct path as per the arrow line H3 in Fig. 2 for gas flow under this duct, and a much longer path (per arrow lines l2) behind and above the said duct.

(7) By also having the upper; part of this water duct curved concentric with the arched top portion of my hood-like member I provide parallel curved walls for guiding the flow of gases along the more circuitous path in which the gases contact with afar greater area of themterior surface of the said member thanwhen flowing along the said shorter path. g (8) When c'onstructedand disposed as in Fig.

2, my damper can readily be positioned effe'ctively either to close the shorter path, divide the gas flow between the previously described two paths, or (as shown in dotted lines) freely open the shorter path and also check the flow along the longer one.

(9) By using a forward portion of the casing bottom and a portion of my water duct as stops for limiting the movements of my damper, I also avoid the need of separate elements for these purposes.

Moreover, it is to be understood that the drawings are merely illustrative of an embodiment of my invention which has proven to be advantageously proportioned, and that many changes might be made without departing either from the spirit of my invention or from the appended claims.

I claim as my invention:

1. A fiue-gas-heat utilizing water heater, comprising a casing having a gas inlet in its bottom and a gas-outlet in its forward end; an upright hood-shaped member housed by the casing and having the lower and the forward edges of the hood sides sealed respectively to the casing bottom and the forward casing end, the said member conjointly with a forward portion of the said bottom forming an elbow connecting the said inlet and outlet; the said member being freely spaced from the top, rear and side walls of the casing to afford a hood-shaped water-containing chamber therebetween; and a horizontal duct spanning the sides of the hood-shaped member and opening at its ends through the said sides to afford a water passage connecting the portions of the water chamber which are respectively at opposite sides of the hood-shaped member, the duct being freely spaced from the top and back of that member, the forward end of the casing and the casing bottom.

2. A water heater as per claim 1, including also a damper movably disposed within the hoodshaped member for controlling the flow of gases from the gas inlet to the gas outlet through the spaces both below and above the water duct.

' 3'. A water heater as per claim 1, including also a damper movably disposed within the hoodshaped member for controlling the flow of gases from the gas inlet to the gas outlet; the damperbeing pivoted at one end on an axis parallel to that of the water duct and near the bottom of this duct, and being movable from a forward downwardly sloping position in which the forward end of the damper engages a forward portion ofthe-bottom of the casing, to a forward upwardly sloping position in which the damper slopes upwardly forward and close to the water duct.-'

4. A water heater as per claim 1, in which the hood-shaped member comprises two riser sides respectively parallel to the two riser sides of the casing, a rear portion extending upwardly from 'the'bottom of the casing parallel to the rear wall of the casing, amajor top portion arching forwardly freely above the water duct from the top of the said rear portion of the hoodshaped member and terminating rearwardly of the said forward casing end, and a shorter sec,- ond top portion sloping forwardly upward from the forward end of the said top portion and sealed at its forward end to the forward wall of the casing.

5. A water heater for association with an oilburning furnace which has a combustion gas outlet in its top, comprising: .a casing having a bottom gas inlet connectible to the said gas outlet and a lateral outlet connectible to a flue; a fine elbow housed by the casing and connecting the said gas inlet with the said outlet of the easing; the elbow having its axis in a vertical plane, and having a duct extending at right angles to the said plane through a part of the elbow and opening at each side of the elbow; and an oil pre-heating pipe extending freely longitudinally through the said duct and also through two opposite sides of the casing, the oil pipe being exteriorly sealed to the said casing sides.

6. A water heater as per claim 5, in which the hood-shaped elbow has flat riser sides respectively parallel to the sides of the casing, and has its back and top consisting of a flat strip formed to present an upright back portion integral with a top portion arching above the water duct, the said duct being spaced by an approximately uniform distance from the said back and arched portions and by a greater distance from the bottom of the casing.

7. A water heater as per claim 5, including a pair of axially alined horizontal journals extending below and parallel to the said duct and respectively reaching from opposite sides of the flue elbow to the two sides of the casing; a damper shaft journaled in the said two journals and extending transversely through the said casing and elbow; and a damper disposed within the said elbow and having one edge thereof formed integral with and within the said casing and connecting the said bottom inlet with the gas outlet of the casing; the said elbow being spaced from the back, top and sides of the casing to afiord a water-containing chamber which straddles and extends behind the elbow, and

III

which chamber reachesfrom the bottom. to the top of the casing; a water-duct spanning. and,

opening through the two sides of the elbowand freely, spaced; from the top and back of theelbow; and an oil pipe extending transversely through the casing and freely through the water duct, the oil ductbeing exteriorly, sealed to the sides of the casing.

9. A fiue-gas-heat utilizing water heater comprising a casing having a gas inlet and a gas outlet respectively in its bottom and in its forward end; an upright hood-shaped member sealed at its lower edges to the casing bottom and at its forward edges to the forward casing end and corresponding in width to the bores of the said inlet and outlet, the said inlet and outlet having their axes in the medial and longitudinal vertical plane of the hood-shaped member; the said member conjointly with the casing afiording a hood-shaped water chamber straddling and extending behind that member; a horizontal water duct disposed transversely of the axis of the said outlet and spanning and opening through the sides of the hood-shaped member; the said duct having a vertical exterior diameter not materially exceeding approximately one-third the maximum interior height of the hood-shaped member, and the said member being formedv to aiford a gas passage-Way of approximately uniform cross-sectional area behind and above the said duct; and the duct being disposed at an elevation affording a second gas passage-way of more than the said cross-sectional area below the duct.

10. A-wat'erheater as per claim 9, including a damper'movably supported-within the hoodshaped member; the damper being movable for selectively controlling the flow of gases through the saidtwo passage-ways.

11. A water heater as per claim 9 including a damper supported within the hood-shaped memher, the damper being movable from a closed position in which it checks the flow of gases to the casing outlet through the said second passageway: so as to compel nearly all of the gases to flow behind and over the top of the water duct, to ,partly open positions in which the damper permits. gasesto flow under the Water duct along relatively shorter paths and to a full open position in which the damper also effectively checks the flow of gases behind and over the water duct through the first named passageway.

12. A water heater as per claim 1, in which the hood-shaped member comprises two riser sides respectively parallel to the riser sides of the casing, a hood back parallel to the rear end of the casing, a major top portion extending forwardly from the upper end of the hood back part way toward the forward end of the casing and arching above the said duct substantially concentric with the upper side of the duct, and a shorter forward top portion reaching from the forward end of the said major top portion to the forward end of the casing.

RALPH H. FJELLMAN. 

